1. Field of the Invention
The present invention relates to a pivoting stair assembly for a work machine. In particular, the invention comprises a pivot structure for supporting a stair assembly for pivoting movement on a landfill compacting tractor.
2. Description of Related Prior Art
Many work machines, such as heavy compacting machines, include stair assemblies located along one or both lateral sides of the machine to facilitate an equipment operator accessing the cab of the machine. In addition, it is known to locate such stair assemblies over at least one of the wheels of the machine in order to further act as a fender to limit travel of debris flung up by the wheels. The stair assemblies are often located adjacent to removable access panels in the lateral sides of the machine, requiring removal of the stair assembly from the side of the machine, and in the case of compacting machines, removal of an associated wheel to access the access panels. The Caterpillar model 386 compactor is one known compacting machine, including steel wheels which weigh up to 10,000 pounds, such that it is necessary to first remove the stair assembly from the area of the wheel in order to attach lifting equipment, such as a crane, to the wheel for lifting the wheel away from the machine.
One known solution to facilitate servicing of the work machine is the provision of a pivot for the stair assembly which enables the stair assembly to be partially pivoted away from the side of the work machine. The known structure places the pivot inwardly from the outer edge of a deck or platform located adjacent to the cab for the machine. The pivot permits the stair assembly to move only about 90° from its operational position over the wheel to an open or access position spaced from the machine. The access position for the stair assembly locates the stair assembly generally over the longitudinal axis of the wheel, such that it is necessary for the lift equipment to work around the stair assembly, including moving the stair assembly to different positions, during the process of removing the wheel. Specifically, the wheel removal process requires that the wheel be moved partially outwardly from the machine after the stair assembly has been pivoted to its access position, and the stair assembly must subsequently be moved to its operable position adjacent the machine before reattaching the lift equipment to the wheel and performing the final operation of lifting the wheel away from the machine.
A further drawback associated with the above described pivoted stair assembly is that the machine requires a large work space to accommodate pivoting of the stair assembly within the service area. Also, if it is desired to move the machine through the service area doorway with the stair assembly located in the access position, most service area doorways would not be capable of accommodating the large width formed by the stair assembly when in the 90° access position.
Accordingly, there remains a need for a stair assembly on a work machine, including an associated pivot structure, which facilitates movement of the stair assembly from its operational position to an access position. Additionally, there is a need for such a stair assembly which positions the stair assembly in a relatively compact location adjacent the machine and which provides substantially unimpeded access to a wheel of the machine.